Eyewear comes in a variety of shapes and sizes. There are different eyewear for different applications. Tinted eyewear is commonly used for both prescription and off-the-shelf sunglasses. Typically, sunglass lenses are tinted in a bath of tint solution. The more time the lenses spend in the bath, the more tint they absorb. Typical tint levels range from 20 percent up to about 80 percent. Lenses with 20 percent tint level (density) are usually considered for fashion purposes only, while those with 50 percent tint level are suitable for most activities. A tint level of 80 percent provides maximum protection against the sun. Additionally, photochromic eyewear can change its tint level in response to ambient light conditions. Thus, the tint level of photochromic eyewear can change over time. Some eyewear may include polarized lenses. Polarized lenses serve to block glare by restricting certain angles of light. This helps in limiting eye-strain and can be very helpful to people working in and around water. In addition to polarization and tint level, the tint shade or lens color is another eyewear parameter. For example, yellow lenses filter blue light that sometimes can make focusing difficult. Copper is a tint shade that tends to enhance contrast and boost oranges, reds, and browns. There are many different tint shades available for various activities and fashion purposes. Thus, eyewear is an important part of everyday life.